L295 - Syntax Taiwan

L295DUAL SWITCH-MODE SOLENOID DRIVERPRELIMINARY DATAHIGH CURRENT CAPABILITY (up to 2.5A perchannel)HIGH VOLTAGE OPERATION (up to 46V forpower stage)HIGH EFFICIENCY SWITCHMODE OPERATIONREGULATED OUTPUT CURRENT (adjustable)FEW EXTERNAL COMPONENTSSEPARATE LOGIC SUPPLYTHERMAL PROTECTIONDESCRIPTIONThe L295 is a monolithic integrated circuit in a 15 -lead Multiwatt ® package; it incorporates all thefunctions for direct interfacing between digital circuitryand inductive loads. The L295 is designed toaccept standard microprocessor logic levels at theinputs and can drive 2 solenoids. The output currentis completely controlled by means of a switch-ABSOLUTE MAXIMUM RATINGSORDER CODE : L295Multiwatt 15ing technique allowing very efficient operation.Furthermore, it includes an enable input and dualsupplies (for interfacing with peripherals running ata higher voltage than the logic).The L295 is particularly suitable for applicationssuch as hammer driving in matrix printers, stepmotor driving and electromagnet controllers.Symbol Parameter Value UnitV s Supply voltage 50 VVss Logic supply voltage 12 VV EN, V i Enable and input voltage 7 VV ref Reference voltage 7 VIo Peak output current (each channel)- non repetitive (t = 100 µsec) 3 A- repetitive (80% on - 20% off; T on = 10 ms) 2.5 A- DC operation 2 APtot Total power dissipation (at Tcase = 75 °C 25 WTstg, Tj Storage and junction temperature - 40 to 150 °CAPPLICATION CIRCUITMarch 19931/8

L295CONNECTION DIAGRAM (top view)BLOCK DIAGRAMTHERMAL DATASymbol Parameter Value UnitR th-j-case Thermal resistance junction-case max 3 °C/WR th-j-amb Thermal resistance junction-ambient max 35 °C/W2/8

L295ELECTRICAL CHARACTERISTICS (Refer to the application circuit, V ss = 5V, V s = 36V; T j = 25°C; L =Low; H = High; unless otherwise specified)Symbol Parameter Test conditions Min. Typ. Max. UnitV s Supply Voltage 12 46 VV ss Logic Supply Voltage 4.75 10 VIdIssQuiescent drain current(from VSS)Quiescent drain current(from VS)VS = 46V; Vi1 = Vi2 = VEN = L 4 mAVSS = 10 V 46 mAV i1,,V i2 Input Voltage Low -0.3 0.8High 2.2 7V EN Enable Input Voltage Low -0.3 0.8High 2.2 7I i1, I i2 Input Current V i1 = V i2 = L -100V i1 = V i2 = H 10I EN Enable Input Current V EN = L -100V EN = H 10VVµAµAV ref1, Input Reference Voltage 0.2 2 VV ref2I ref1,I ref2mInput Reference Voltage -5 µAFosc Oscillation Frequency C = 3.9 nF; R = 9.1 KΩ 25 KHzI pTransconductance (each ch.) V ref = 1V 1.9 2 2.1 A/VV refV dropVsens1V sens2Total output voltage drop(each channel) (*)External sensing resistorsvoltage dropI o = 2 A 2.8 3.6 V2 V(*) Vdrop = VCEsat Q1 + VCEsat Q2.3/8

L295APPLICATION CIRCUITD2, D4 = 2A High speed diodesD1, D3 = 1A High speed diodesR1 = R2 = 2ΩL1 = L2 = 5 mH) trr ≤ 200 nsFUNCTIONAL DESCRIPTIONThe L295 incorporates two indipendent driverchannals with separate inputs and outputs, eachcapable of driving an inductive load (see blockdiagram).The device is controlled by three micriprocessorcompatible digital inputs and two analog inputs.These inputs are:EN chip enable (digital input, active low),enables both channels when in the lowstate.V in1, V in2 channel inputs (digital inputs, activehigh), enable each channel independently.A channel is actived whenboth EN and the appropriate channelinput are active.V ref1, V ref2 referce voltages (analog inputs), usedto program the peak load currents.Peak load current is proportional to V ref.Since the two channels are identical, only channelone will be described.The following description applies also the channeltwo, replacing FF2 for FF1, V ref for V ref1 etc.When the channel is avtivated by low level on theEN input and a high level on the channel input, V in2,the output transistors Q1 and Q2 switch on andcurrent flows in the load according to the exponentiallaw:I =VR1( 1 − e− R1 tL1 )where: R1 and R2 are the resistance and inductanceof the load and V is the voltageavailable on the load (V s - V drop -V sense).The current increases until the voltage on the externalsensing resistor, R S1, reaches the referencevoltage, V ref1. This peak current, I p1, is given by:I p1 =V ref1R S1At this point the comparator output, Vomp1, setethe RS flip-flop, FF1, that turns off the output transistor,Q1. The load current flowing through D2, Q2,R S1, decreases according to the law:I = (V AR 1+ I p1 ) e − R1 tL1where V A = V CEsat Q2 + V sense + V D2−V AR14/8

L295If the oscillator pin (9) is connected to ground theload current falls to zero as shown in fig. 1.At this time t2 the channel 1 is disabled, by takingthe inputs V in1 low and/or EN high, and the outputtransistor Q2 is turned off. The load current flowsthrough D2 and D1 according to the law:I = (VBR 1+ IT2 ) e − R1 tL1−V BR1where V B = V S + V D1 + V D2I T2 = current value at the time t 2.Fig. 2 in shows the current waveform obtained withan RC network connected between pin 9 andground. From to t 1 the current increases as in fig.1. A difference exists at the time t 2 because thecurrent starts to increase again. At this time a pulseis produced by the oscillator circuit that resets theflip.flop, FF1, and switches on the outout transistor,Q1. The current increases until the drop on thesensing resistor RS1 is equal to Vref1 (t3) and thecycle repeats.The switching frequency depends on the value Rand C, as shown in fig. 4 and must be chosen inthe range 10 to 30 KHz.It is possible with external hardware to change thereference voltage V ref in order to obtain a high peakcurrent I p and a lower holding current I h (see fig. 3).The L295 is provided with a thermal protection thatswitches off all the output transistors when thejunction temperature exceeds 150°C. The presenceof a hysteresis circuit makes the IC work againaftera fall of the junction temperature of about20°C.The analog input pins (Vref1 , Vref2) can be left openor connected to V ss; in this case the circuit workswith an internal reference voltage of about 2.5V andthe peak current in the load is fixed only by the valueof R s:I p =2.5R SSIGNAL WAVEFORMSFigure 1. Load current waveform with pin 9connected to GND.Figure 2. Load current waveform with externalR-C network connected between pin 9 andground.5/8

L295SIGNAL WAVEFORMS (continued)Figure 3. With Vref changed by hardware.Figure 4. Switching frequency vs. values of Rand C.6/8

L295MULTIWATT15 PACKAGE MECHANICAL DATADIM.mminchMIN. TYP. MAX. MIN. TYP. MAX.A 5 0.197B 2.65 0.104C 1.6 0.063D 1 0.039E 0.49 0.55 0.019 0.022F 0.66 0.75 0.026 0.030G 1.02 1.27 1.52 0.040 0.050 0.060G1 17.53 17.78 18.03 0.690 0.700 0.710H1 19.6 0.772H2 20.2 0.795L 21.9 22.2 22.5 0.862 0.874 0.886L1 21.7 22.1 22.5 0.854 0.870 0.886L2 17.65 18.1 0.695 0.713L3 17.25 17.5 17.75 0.679 0.689 0.699L4 10.3 10.7 10.9 0.406 0.421 0.429L7 2.65 2.9 0.104 0.114M 4.25 4.55 4.85 0.167 0.179 0.191M1 4.63 5.08 5.53 0.182 0.200 0.218S 1.9 2.6 0.075 0.102S1 1.9 2.6 0.075 0.102Dia1 3.65 3.85 0.144 0.1527/8

L295Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for theconsequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. Nolicense is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specifications mentionedin this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied.SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without expresswritten approval of SGS-THOMSON Microelectronics.© 1994 SGS-THOMSON Microelectronics - All Rights ReservedSGS-THOMSON Microelectronics GROUP OF COMPANIESAustralia - Brazil - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands - Singapore -Spain - Sweden - Switzerland - Taiwan - Thaliand - United Kingdom - U.S.A.8/8